Flying on Woody Biomass and Camelina: Consortium Seeks Biofuel Answers

19 january 2013

SEATTLE — Aviation remains as much a part of Washington State as its eastern dry-land agriculture or the rain-soaked forests on its mountainous western fringes. But only the alternative energy industry proposes to combine the three in a regional effort to create a green and renewable jet fuel (biojet).

Boeing, the U.S. Navy, the U.S. Air Force, Lufthansa and Finnair, among others, have all tested aviation biofuel mixes in existing aircraft for use as a drop-in alternative fuel source.  But two separate federally-funded $40 million efforts led by Washington State University and the University of Washington as part of the Northwest Advanced Renewables Alliance (NARA) are aiming to make biojet a regular part of the region’s aviation mix.

NARA’s goal is to ramp up Northwest aviation fuel use to a maximum 50/50 mix of aviation biofuel and conventional jet fuel.  In the Northwest, NARA researchers hope to use both oil seeds and wood residues to fuel biojet production.

“An absolute requirement is that this has to be a drop-in fuel,” said NARA Director Ralph Cavalieri, a biological systems engineer at Washington State University in Pullman.  “The availability of the biojet won’t be uniform worldwide, therefore, the engines will also have to operate on conventional jet fuel wherever they [refuel].”

Until aircraft propulsion technology radically changes, the aviation industry notably has fewer alternative energy choices than other modes of transportation.  Thus, biojet fuel derived from sustainable biomass is a crucial component of the aviation sector’s long-term strategy in both countering carbon taxes and going green.

Camelina, an oil seed in the same family as rapeseed, could help make this happen.  It is normally harvested dry with a wheat combine then crushed to squeeze oil from its seeds.  However, 70 percent of its original volume is leftover after crushing and is subsequently sold as animal feed, mostly for chickens or feedlot cattle.

The plant’s economic prospects are brighter in dry-land agricultural areas because land values in eastern Washington and western Montana can accommodate low-value crops, unlike highly-irrigated farmland in Oregon’s Columbia River basin.

Camelina grown in the Northwest would likely initially be used to fuel aircraft at major area airports like Seattle-Tacoma, Portland and Spokane.

Steve Camp, a farmer in LaCrosse, Washington, has just finished his fifth harvest of some 300 acres of Camelina as part of his crop rotation for dry-land wheat. Until lately, he’s been extracting the oil to make his own biodiesel and selling the remaining leftover meal as animal feed.  Although he’s among only a handful of farmers in eastern Washington growing Camelina, Camp soon hopes to be selling at least part of his annual crop to make commercial biojet.

Even so, Camelina’s biggest challenge in becoming a viable biojet source is arguably its current tiny commercial market.  Because the oil seed plant is still being farmed in such small quantities, Camp says farmers can consider themselves lucky to get 20 cents per pound for the plant’s seeds.

“People who want the Camelina seeds are going to have to pay the farmers enough to make it worth their while economically,” said Cavalieri who notes that Camelina to biojet conversion still remains in the pilot stages.

But, in truth, Camelina represents only one source component of a Northwest biojet market.  The rest will likely come from the Northwest’s remaining vast forests of Idaho, Washington, Montana, and Oregon in the form of wood biomass residuals.

Such residuals are often left in slash piles for burning or otherwise sold for pulp.  But this raw forest biomass also has the added advantage of being less expensive to buy per ton than Camelina.

Yet hurdles remain in converting the wood’s cellulose into sugars that can produce alcohol.  Although termites and certain types of fungi naturally produce enzymes that break down wood structure, in a commercial setting such enzymes are costly.  So, NARA researchers are working on various pre-treatment scenarios to make this enzymatic process more efficient; likely involving “cooking” forest biomass wood chips with chemicals.

“With pulping you isolate the cellulose out of the wood,” said Michael Wolcott, a materials engineer at Washington State University in Pullman.  “But [to produce biojet] we don’t have to isolate it.  We just have to make it more accessible to [commercially-produced] enzymes which break down the carbohydrates into fermentable sugars.”

Cavalieri says Gevo, Inc. in Englewood, Colorado has a proprietary line of microbes that will ferment sugar and produce isobutanol (an alcohol) that’s readily converted into biojet and other products.

But there are no large scale plans to do so now.  One reason arguably involves lignin; the “glue” that binds a tree’s cellulose.

“Lignin is difficult to break down and not useful for making the sugars that the microbes need to [produce] the alcohols that ultimately become jet fuel,” said Cavalieri.  “But because you’re paying for it as part of the weight brought into the processing plant, you need to convert it into something more valuable.”

Thus far, softwood conifers like Douglas fir, Western hemlock, and Ponderosa pine, says Cavalieri, have been the most difficult to convert to biofuel.  That’s because typically some 30 percent of the softwoods are made up of lignin.

“Softwoods are lower in carbohydrate content from which sugars can be produced,” said Wolcott.  “That means you have to develop a market for these non-fermentable materials.  We would use the lignin as a raw material to produce a component of thermoplastic and thermo-setting polymers.”

Once the wood conversion technology is fine-tuned, Cavalieri hopes that now shuttered portions of the Northwest’s pulpwood industry infrastructure can be “re-purposed” to produce biojet.

While Colorado-based companies like Gevo and Zeachem are both separately working on forest biomass conversion to biojet technology, commercial production has yet to begin.

But if the Northwest can find a way to being commercial biojet production from either oil seeds like Camelina or woody biomass, the benefits would likely ripple across the country and spur follow-on biojet development elsewhere.

Today, commercial and military aviation in the Northwest use some 800 million gallons of fuel each year.  Thus, to meet a maximum 50/50 blend of biojet to conventional jet fuel would require at least 400 million gallons be derived from biomass.

Northwest Camelina is expected to eventually cover as much as half of that figure, with biojet from forest biomass projected to make up the needed annual remainder.

Within two decades, Cavalieri envisions Northwest-produced biojet being able to meet the needs of the region’s aviation fuel market.  But beyond that, any future growth in Northwest biojet production will likely be heavily dependent on local forest biomass.